Method of printing



May 9, N39. VA. E. GESSLER ET AL J 3 METHOD OF PRINTING Filed Jul 25,1955 Patented May 9, 1939 UNITED STATES METHOD OF PRINTING Albert E.Gessler, Ardsley-on-Hndson, and Albert F. Guiteras, New York, N. Y., andCharles F. Clarkson, Philadelphia, Pa., assignors to Intel-chemicalCorporation, a corporation oi Ohio Application July 25, 1935, Serial No.33,078

23 Claims. (01. 101- 416) This invention relates to a method of printingand is directed to a rapid drying of printed matter printed with an inkwhich does not dry on the press.

In carrying out our method, we use a printing ink whose vehicle consistsof a tendacious, solid binder or thickener dissolved in a solvent whichis practically non-volatile at room temperature, so that the ink doesnot dry on the ink distribut- 0 ing parts of the press.

Our method for rapidly drying printed matter printed with such an inkconsists in replacing the bulk of the non-volatile solvent in theprinted film of ink with a volatile liquid which is miscible with theink solvent but a non-solvent for the ink binder. This substitution notonly precipitates the ink binder, but also leaves the ink film wet onlywith a volatile liquid which quickly evaporates at room temperature,leaving the printed matter dry without the long delay or the applicationof high heat which would have been necessary for drying had the originalnonvolatile solvent remained in the ink film.

The replacing oi the non-volatile solvent with the volatile liquid iseffected by diluting the nonvolatile solvent with the volatile liquidand then removing all or the greater part of the mixture of non-volatilesolvent and volatile liquid item the ink film so as to leave the filmwet with a liquid which is wholly or mainly volatile at roomtemperature. The replacement is most desirably eflccted in such a way asto leave as small an amount of liquid as possible on the printed matter.This small amount oi volatile liquid quickly evaporates at roomtemperature leaving the printed matter dry a few moments after it isprinted.

The particular diluent used in the method depends upon the character ofthe solvent oi the ink. For reasons of economy, it is desirable to usewater as the diluent. To permit this it is necessary to use as thesolvent in the ink a liquid which is miscible with water and whichbecomes a non-solvent for the binder of the lot. on dilu tion withwater. Solvents of this character in clude diethylene glycol, diethyleneglycol monoethyl acetate, diethylene glycol monohutyl ether, andtetraethylcne glycol monomethyl ether acetate. We give a few specificexamples of inks which may be set by the method of our invention, usingwater as the diluent:

These inks are dispersions oi coloring matter in organic viscousvehicles consisting of a liquid component and a thickening agent orbinder for the coloring material dissolved in the liquid component insufilcient quantity to give the ink the consistency of an ordinaryoil-varnish printing ink. The liquid component, having a vapor pressureat 20 C. as low as the vapor pressure of diethylene glycol monobutylether at 20 C., is practically non-volatile at room temperatures. andthe ink is stable under ordinary press room printing conditions. Theliquid component is miscible with the diluent employed.

Another convenient diluent for use in our method is ethyl alcohol.Additional diluents may be suitable members of the hydrocarbon class orother solvents not dissolving the binder and being 25 miscible with thesolvent of the ink. A suitable hydrocarbon derivative is, for instance,dichlorethylene. Alcohol can be used with inks whose solvents are notwater-miscible, but are miscible with alcohol. We have found that thesolvent diethylene glycol monobutyl ether acetate is miscible with ethylalcohol and becomes a nonsolvent for cellulose compounds or resins whendiluted with as little as 8% to 15% of alcohol. We give specificexamples of inks which may he set by our method, using alcohol as thediluent:

Example III Parts by weight so Permanent Peacock blue RS nitrocelluloseA, second viscosity (wet with 30% alcohol) 3d Diethylene glycolmonobutyl ether acetate 40 Example IV M Parts by weight Carbon black l iPrussian blue 6 Ester gum 4'7 60 Diethylene glycol monobutyl etheracetate" 31 White petrolatum 2 Both the diluents mentioned, water andalcohol, are much more volatile than the solvents of the inks ofExamples I to IV.

The particular manner in which the diluent is applied to the printedsheet and in which the mixture of diluent and solvent is removed fromthe printed sheet constitutes an important subto tact with the printedsurface.

One method consists in causing a stream of the diluent to flow or sprayon and across, and then away from, the printed surface. This method isdesirable when the diluent is inexpensive and when the character of thematerial on which the ink is printed is such that the material is notinjured by a stream of diluent flowing across it. It may be used toadvantage where the diluent is water and the material is Cellophane,parchment, or a heavily glazed paper.

This method is illustrated in Figs. 1 and 3 which show a long strip ofsheet material Ill passing through a printing press I I which appliesink to its upper surface, and then over to roller supports l2 which holda portion l3 of the sheet material in an inclined position. A spigot orspray nozzle l4 directs a stream of the diluent upon the printed surfaceof the inclined portion l3 of the sheet. The stream passes rapidlyacross the inclined portion l3, and off the lower edge of this portionand-into a catch-pan l5. In passing across the printed matter, thestream of diluent dilutes the solvent in the ink so as to precipitatethe binder, and carries the greater part of the diluted solvent into thecatch-pan before any substantial evaporation of the diluent mixed withthe solvent-can occur."- I

The other method consists in distributing the diluent in closely spacedcapillary cavities and moving each cavity into contact with a small areaof the printed surface and then out of con- This method is applicablewhere the material to which the ink has been applied is ordinary paper,as it involves little wetting of the material by the diluent.

This method is illustrated in Figs. 2 and 4, which show a long strip orweb of sheet material 20 passing through a printing press which appliesink to the upper surface of the material, then around roller supports 22which invert the web so as to place its printed surface downward. Theweb is then drawn over the upper portion of a cylinder 23 whose lowerportion is in a trough 24 in which the diluent is placed. Thecylindrical surface of the cylinder 23 is provided with closely spacedcapillary cavities 25 shown in the magnified Fig. 4. These cavities maybe made by etching, and the cylinder 23 may be either a grained cylindersuch as is used in lithography, an etched copper cylinder like a uniformtone half-tone plate, or a roller covered by cloth or the like. Thecylinder 23 is rotated so that its surface travels at the same speed asthe travelling web to avoid rubbing action between them. As the cylinderrotates, the cavities in its lower side are filled with the diluent inthe trough 24.

The filled cavities pass under a doctor blade 26 which removes anyliquid adhering to the raised portions of the cylindrical surface, butleaves the cavities full of the diluent which is held in them bycapillary action. As the filled cavities pass across the top of thecylinder, the liquid in them comes in contact with small closely spacedareas of contact with the sheet, they carry away from the precipitatedbinder the greater part of the diluted solvent. This is because eachcavity, although small, retains a volume of liquid materially largerthan the volume of solvent in the area of the ink with which it comes incontact.

In the arrangement illustrated, the solvent extracted from the inkbecomes diffused in the diluent in the trough 2i. By changing the liquidin the trough 24 or by providing for a circulation through the trough24, the concentration of the solvent in the diluent in the trough iskept low so that the liquid carried out from the trough in the cavitiesdoes not contain a sufficient amount of the solvent to prevent it fromdiluting the solvent in the ink with which it comes in contact.

In this method some of the cavities necessarily come into contact withthe surface of the web 20 between the areas to which ink has beenapplied. The volume of liquid held in the cavities is, however, so smallthat there is no substantial wetting of the web by the diluent.

In this specification and the claims which follow, we have used thewords "solvent and "nonsolvent to mean capable or incapable of formingwith the binder of the ink a solution, in the ordinary sense of thatterm which includes both true solution and colloidal dispersions.

What is claimed is:

1. The method of setting a printing ink whose vehicle comprises a binderdissolved in a solvent which is stable on the press, which consists indiluting the solvent of the ink on the printed matter with a morevolatile non-solvent to precipitate the binder, and removing the greaterpart of the mixture of solvent and non-solvent from the precipitatedbinder before evaporation of the non-solvent.

2. The method of setting a printing ink whose vehicle comprises acolloid dissolved in a solvent which is stable on the press, whichconsists in causing a stream of a non-solvent liquid more volatile thanthe solvent and miscible therewith to flow across and away from theprinted surface of the printed matter without coming in contact with therear face of the printed matter.

3. The method of setting a printing ink whose vehicle comprises a binderdissolved in a solvent, which consists in placing the printed matterwith its printed surface downward, filling an open-top receptacle with anon-solvent liquid miscible with the solvent of the ink and morevolatile than that solvent, and moving said receptacle so as to bringthe upper surface of the liquid therein into conaromas 5. The method ofsetting a. printing ink whose vehicle comprises a binder dissolved in asolvent, which consists in distributing a non-solvent liquid misciblewith the solvent of the ink and more volatile than that solvent in aplurality of closely spaced capillary cavities, and moving said cavities'so as to bring them into contact withthe printed surface of the printedmatter and then out of contact therewith.

6. The method of setting a printing inkwhose vehicle comprises a binderdissolvedin' a solvent, which consists in passing the printed matterprinted side downward over the upper surface of a roller containing apluralityof closely spaced cavities, rotating said roller in synchronismwith the movement of the printed'matter, filling the cavities with anon-solvent liquid miscible with the solvent of the ink before thecavities reach theupper surface of the roller, and removing the mixtureof non-solvent and solvent from the cavities after they pass the uppersurface of the roller;

7. The method of setting a printing. ink whose vehicle comprises abinder dissolved in a solvent, which consists in passing the printedmatter printed side downward over the surface of a roller containing aplurality of closely spaced capillary cavities, rotating said roller insynchronism with the movement of the printed matter, and filling thecavities of said roller with a non-solvent liquid miscible withthesolvent of the ink.

8. The method of setting a printing ink whose vehicle comprises a binderdissolved in a solvent, which consists in passing the printed matterprinted side downward over the upper surface of a roller containing a.plurality of closely spaced capillary cavities and having its lowersurface in atrough, rotating said roller in 'synchronism with themovement of the printed matter, filling the trough with a non-solventliquid miscible with the solvent of the ink which is carried to theprinted matter in the cavities of the roller and returned to the troughmixed with the solvent of the ink, and changing the liquid in the troughso as to maintain a low concentration of the solvent therein.

9. The method of printing which comprises dissolving a binder in asolvent. which is stable on the press, mixing a pigment in saidsolution, printing a film of said pigmented solution on a sheet,diluting the solvent in the film on the sheet with a non-solvent morevolatile than the solvent to precipitate the binder on the sheet, andremoving the greater part of the diluted solvent from the precipitatedbinder before evaporation of the diluent.

10. The method of printing which comprises dissolving a water-insolublebinder in a watermiscible solvent which is stable on the press and lessvolatile than water, mixing a pigment in said solution, printing a filmof said pigmented solution on a sheet, diluting the solvent in the filmon the sheet with water to precipitate the binder on the sheet, andremoving the greater part of the diluted solvent from the precipitatedbinder before evaporation of the water.

11. The method of printing which comprises dissolving a water-insolublebinder in diethylene glycol monobutyl ether, mixing a pigment in saidsolution, printing a film of said pigmented solution on a sheet,diluting the solvent in the film on the sheet with water to precipitatethe binder on the sheet, and removing the greater part of the dilutedsolvent from the precipitated binder before evaporation of the water.

12. The method oi treating printed printing ink'with a liquid withoutsubstantial wetting of the material on which the ink has been printed,which consists in distributing the treating liquid in a plurality ofclosely spaced capillary cavities and moving said cavities so as tobring them into contact with the printed surface of the printed matter.

13. The method of setting a printing ink whose vehicle comprisesa.binder dissolved in a solvent, which consists in bringing only theprinted surface of the printed matter into momentary contact with anon-solvent liquid more volatile than the solvent and miscible therewithto extract the 15. The method of printing which comprises.

dissolving a binder in a solvent which is practically non-volatile atroom temperature, mixing a pigment in said solution, printing a film ofsaid pigmented solution on a sheet, bringing a nonsolvent liquid morevolatile than the solvent into contact with only the printed surface ofthe sheet to dilute the solvent in the film on the sheet to precipitatethe binder on the sheet, and removing the greater part of the dilutedsolvent from said surface of the sheet before substantial penetration ofthe liquid into the sheet.

16. The method which comprises printing upon.

a continuously traveling web with an ink whose vehicle comprises acolloid dissolved in a solvent,

causing approaching and separating movements between the printed surfaceof the web and a non-solvent liquid miscible with the solvent to bringeach successive portion of only the printed surface of the traveling webinto momentary contact with said liquid, whereby the solvent isextracted from the ink on the web to precipitate the binder on the web.17. The method which comprises printing upon a continuously travelingweb with an ink whose vehicle comprises a binder dissolved in a solvent,inclining a portion of the printed traveling web at an angle to thehorizontal with one edge higher than the other and with its printedsurface uppermost, and causing a stream of a non-solvent liquid morevolatile than the solvent and miscible therewith to flow across and awayfrom the uppermost surface of said inclined portion of the web.

18. The method which comprises printing upon a continuously travelingweb with an ink comprising a coloring material and a vehicle thereforcontaining a binder and a solvent with a suflow vapor pressure to makethe ink stable on the press, thereafter momentarily contacting theprinted surface of the sheet with a liquid which is miscible with thesolvent, which is a non-solvent i'or the binder and pigment. and whichis more volatile than the solvent, and immediately removing said liquidfrom said surface of the sheet, whereby the ink is set to a state ofsubstantial dryness.

20. A method for rapidly drying printed matter carrying a film of inkcontaining a binder dissolved in a relatively non-volatile solvent,which comprises causing a stream of a relatively volatile non-solventliquid miscible with the ink solvent to flow across and away from theprinted surface of the printed matter to extract the relativelynon-volatile ink solvent and leave the printed matter wet withrelatively volatile liquid.

21. A method for ramdly drying printed matter carrying a illm of inkcontaining a binder dissolved in a relatively non-volatile solvent,which comprises placing the printed matter with its printed surfacedownward, filling an open-top receptacle with a relatively volatilenon-solvent liquid miscible with the solvent in the ink, and moving saidreceptacle so as to bring the upper surface of the liquid therein incontact with the printed surface of the printed matter to extract thesolvent from the ink iilm and leave the printed matter wet withrelatively volatile liquid.

22. Method of printing and rapidly drying the printed matter whichcomprises printing a thin film of ink containing a binder dissolved in anonvolatile solvent on the surface of a sheet,momentarilycontactingsaidiilm ofinkonthe printed sheet with a relativelyvolatile non-solvent which is miscible with said solvent, andimmediately removing the bulk of the solvent and non-solvent from thepresence of said iilm and sheet, whereby to avoid immersing and soakingthe sheet, and also to avoid subjecting the sheet to the hightemperature required for rapidly evaporating said solvent.

23. In the method which comprises printing on paper with an inkcontaining a binder dissolved in a non-volatile solvent. the steps whichcomprise momentarily contacting said illm of ink on the paper with arelatively volatile non-solvent which is miscible with said solvent, andimmediately removing the bulk of the solvent and nonsolvent from thepresence of the dim and sheet, whereby the ink is rapidly set andimmersion and soaking of the sheet are avoided.

' ALBERT E. GESSLER.

ALBERT 1". GUII'ERAS. CHARLES I". CLARKSON.

